Python Strings - Part 1

A string is a way of representing text in Python. It could be a word, a sentence, or even a single character. Strings are always written inside quotes so Python knows it’s text and not code.

Examples:

print("Hello")
print('Good morning')
print("12345")   # Even numbers in quotes are strings!

Notice that "12345" is different from the number 12345. The first one is a string (text), while the second one is a number (integer).

You can use either single quotes ('...') or double quotes ("...") to make a string. Both work the same — you just need to make sure the opening and closing quote match.

Try this

Print your name using single quotes.
Print your favourite food using double quotes.
Try printing "12345" (as a string) and then 12345 (as a number). Can you see the difference?

Printing strings

The print() function shows text on the screen. Think of it as a way of telling Python: “Display this for me.”

print("Welcome to Python!")

You can also print more than one piece of text at once by separating them with commas:

print("Hello", "world")

Python automatically adds spaces between the different items when you use commas.

Try this

Print "Python is fun" to the screen.
Print "I love", "pizza", and "chips" in one line using commas.
Try printing the same three words joined together without commas: print("I love" "pizza" "chips"). What happens?

Joining strings (concatenation)

You can join strings together using the + symbol. This is called concatenation (joining).

Example:

first = "Hello"
second = "World"
print(first + " " + second)

This prints:

Hello World

Notice we added " " (a space inside quotes) to make sure the two words didn’t get squashed together.

You can join more than two strings together:

greeting = "Good" + " " + "morning" + "!"
print(greeting)

Try this

Make two variables: first_name = "Alice" last_name = "Smith"
Join them together to print your full name.
Try adding a space between them.

Length of a string

Python can tell you how many characters are in a string using the built-in len() function. Characters include letters, numbers, spaces, and punctuation.

word = "Python"
print(len(word))   # 6

Each letter is counted, starting from the first P all the way to the last n.

Spaces and punctuation also count:

sentence = "Hello, world!"
print(len(sentence))   # 13

Try this

Make a string with your favourite animal, e.g. "elephant".
Use len() to find out how many letters it has.
Try adding a space to the string, e.g. "elephant animal". What happens to the length?

Accessing characters by position

Strings are like a row of characters in order. Each character has a position, called an index. In Python, the first position is 0, not 1.

Example with "Python":

 P   y   t   h   o   n
 0   1   2   3   4   5

To get a character, use square brackets [ ] with its position:

word = "Python"
print(word[0])   # 'P'  (first letter)
print(word[1])   # 'y'
print(word[5])   # 'n'  (last letter)

If you try to use a position that doesn’t exist, Python will give an IndexError. For example, "Python" has 6 characters, so the highest index you can use is 5.

Try this

Create fruit = "apple".
Print the first letter.
Print the last letter. (Hint: the last position is 4 because "apple" has 5 letters.)
Try printing fruit[10]. What error do you get?